Electric heater



April 13 1926. y

l c. c. ABBOTT ELECTRIC HEAT'ERA' Filed Nov. 26, 1924 Fig. 5.

ZINC

iff/117676717 .5111/1 Patented Apr. 1926.v

' *UNITED STATES PATENT-f orifice.) a

CHLARLES C. ABBOTT, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TBIC COMPANY, -A CORPORATION F NEW YORK. l

ELECTRIC HEATER.

Application led November 26, 1924. Serial No. 752,447.

To a whom it may cof/wem:

Be it known that I, CHARLES C. Ano'rr, a citizen of the United States, residing `at Pittsfield, in th'e county ofBerkshire, State of Massachusetts, have invented certain new and useful Improvements in Electric Heaters, of which the following is a specification;-

`My invention relates to electric heaters, and. has for its obect the provision of an electric heater including means for disconf necting theheating units from the electrical supply source upon the occurrence of an excessive temperature.

My invention relates more particularly to electric lheaters for oil wells. Such heaters are lowered into the well and are usedvto melt various deposits, such as parain, which tend to clog 'up the well and 'prevent the free flow of oil. The heaters during operar tion, therefore, are not accessible and it is impossible to observe the conditions4 under which they operate. There is no way of ascertaining whether the heater is o erating atan excessive temperature and this might often occur with resultant damage to the heater.

In car ing out. my invention I incorporate suita le protective means in the heater whereby it is automatically disconnected from the electric supply circuit uponthe occurrence of a temperature which may' dam- Viss age, it.

For a more complete understanding of my invention, reference should be had' to the ac eompanying drawing, in which Fig. 1 is an'` elevation view in section of an electric heater ing material The lower endsof the units 10 are connected to a'lower head member 14, for example, by threading the ends of the sheathsas indicated at 15 and screwing Ythem into tapped holes in the member 14. Immediately'above the member 14, the

`units are bent inwardly together slightly so .1 -as to rest against the metallic pipe '16` and extend longitudinally thereof. Clam ing members 17 are provided at intervals a ong the length ofthe heating units 10 whereby the units are secured tightly against pipe16 1n good heat'cond'uctin ,relation therewith. 4 The pipe 16 is somew at longer than the units 10 and has its upperend threaded at 18 and screwed tightly in a tapped hole in an upper head member 19. The member 19 is providedwith a;boref20 irr which the ends of the units extend and are held' tightly clamped in groper spacedV relation ainst the pipe 16 y means of radially e set screws 21 in member 19.' As shown .1n

Fig. 2 the setv screws 2`1 are spaced at interembodying my invention; Fig. 2 is an en-` larged sectional view looking upward along the line 2--2 of Fig. l; while Fig. 3 is an enlarged elevation vie'w in section showing details of the temperature protective device.

Referring to the drawing, in one form of my invention I utilize electric heating units of the helical coil sheathedwire ty'pe such as described and claimed in my Patent No.

1,367,341, dated February 1, 1921. Thev heating means consists of a plurality of fminals 22' which may be insulated from thev vals around the periphery f member 19 and other meta lic parts of the heater. Atil their i rlower ends the resistance conductors are brought out and connected to suitable ter# sheaths of. the' units by insulating washers 23. The `terminals 22 of the units are electrically. connected by 'means of members 24 lengths 10.0f this helical coil sheathed wire 1 unit, seven being shown. These lengths are spaced in Vparallel relation around thecir# cumference of a circle as shown in Fig.i2. It will be understood that each of these units consists of an outeinetallic sheath 11 in which'is a helically. shaped resistanc'econductor 12 embedded .in compactedY insulat-` to a. common connector ring 25 which is in turn electrically connected through flexible conductor strip 26 to ,the lower end of a 100 conductor rod 27 extendingupward centrally ofthe pipe 16.- At intervalsalong the length of the rod '27*aresuitable fusible devices 28 which are arranged -to'break the."

electric circuit` for the heating units uponf105 thejoccurrence of an excessive tem rature. The upper end of, rod'27 isf, electrically secured-toa terminal 29 which extends centrally through the bottom Aofmetallic receptacle member and .is secured to the mem- 110 nding bei 30 in insulated relation therewith. Pref-V t-'rably the terminal `29 is inserted in 'an insulatlng bushing 31 which is secured 111 a lmetallic bushing 32 having its upper end -provided with a flange 33 and its lower end* threaded so that it may be secured to the member by means of a suitable nut 34. Acoupling 35 may be provided for connecting" rod 27 to the lowerv end of the terminal 29. The receptacle member 30 has its lower end threaded at 36 and screwed tightly in -a tapped bore 37 in the upper end of nien1- ber 19. Y

A helical spring 38 is provided .on the lower end of rod 27 and seated on the terminal ring 25. `When the rod 27 has been secured in place to the terminal 29 this spring is under compression vso that when any one or more of fuses 28 melts the lower portion of rod .27 l\,will be forced quickly downward by spring 38 s'Q asto assure 4a quick and effective opening of an electric lheating circuit. .The heater is sealed at its lower end by means of a metallic cap member 40, the upper end of which is threaded t l at '41"and lsecured tightly in the tapped bore of member 14. In order to permit the lower end of rod v27 to be forced downwardfor an appreci-able distance and thus assure the opening of the heating circuit; the member y40 is elongated and provided with an elongated bore 41. to receive the end of rod 27. Preferably 'ea cylindrical insulator 42 is provided in the bore 41 for insulating the conducting strip 26 from the member 40. Insulating tubes 43 are provided at intervals f A on the rod 27 to. prevent its coming in contact with pipe 16.

As shown in Fig. 3, each ofthe fuses 28 may comprise an outer tubular member 45 made of aluminum. This member 45 'is tapped at eachl en d a considerable distance and has inserted in it ashort rod 46 made of-zinc. This rod 46 may be secured in place by means of screws 47 and 48 inserted 1n the ends of member 45. The screws are seated tightly against the ends of the zinc bar 46 and secure it rigidly as well as forming a 4 goed electrical connection. These fuses 28 'are inserted by threading the ends Of thevarious sections of the rod 27 and T'screwing-them tightlyin the fuses which form mechanical and electrical connections between the sections. Peripheral grooves 49 and 50 are provided in the member 45 near the respective ends of rod 46. .The object of l .occur at Some point alo the-groovesis to reduce theA cross section of the member 45at these points and thus asoccurrence'of an excessiv temperature vwill g the length of the zinc rod 46. i

rI he purposev of the zinc rod is to smother the arc formed by `rupture of the'heating circuit.'v It will be-understood that the kiloto its armor.

watt capacity of heaters-of this type is fairly large and conseqii/etly there is a correspondingly large'cu'rrentto be ruptured. The zinc. melts at a lower temperature than the aluminum and will vbe in a molten condition when the member 45 has been weakened to such an extent that spring 38 will break it. The oxide fumes ofthe zinc quickly smother the arc. A plurality of fuses are -used t0 provide against local overheating at some point along the length of the heater. j

'lhe fuses operate to open the circuit ata temperature somewhat less than the 'maxii'num safe operating temperature of the heatlng units.

A'metalliccap 51 is preferably screwed on the tapped upper end of member 30. A central bore 52 is provided in the c ap 51 through which a suitable electrical cable 53 extends? This cable is preferably armored and forms the support for the heater by means of which thesheater is lowered into the well. It is also provided with a central insulated electrical conductor for supplying )the heating units. The returnelectrical circuit for 'the heating units is through the armor of the cable.

In order to form a mechanical and also 'i electricab connection between the armor of the cable 53 and the outer metal parts of the heater, ,the wires 54 forming the armor of the cable are secured between a -central ring member 55 and two outer ring members 56 and 57. For example, the outermostlayer of wires are bent outward between the rings 55 and 56 while the next layer of wires are bent outward between therings 55- and 57.

' The rings are then clamped tightly together by means of bolts v58. As an additional means of securing the ends of the-wires the -central ring 55 may be provided with a slipped down over the rings and screwed on the member;` 30, the .cable and member 30 being held lfrom twisting. The cap 51 isl screwed Adowntightly on" the head formed by"v the rings, Iwhereby the 'head is clamped .be-

The central insulated conductor 62 ofl the cable is connected to the terminal 29. .A cirwv cuit is thus completed lead-ing through rod 27, the flexiblestrip 26, and washer-25 to the resistor conductors in the various units,

and then through the resistance conductors tween the cap and the upper end of member i ysu r tl1at rupture of Irtiber 45 upon the 30 .1.25

to the outer metallic parts of theheater, the return circuit being completed through the armor 53 of the cable.

TheV -heaterv is thoroughlysealed at 'the .upper end by means of a suitable insulating material 63, such as an asphaltic compoundy which is poured in a molten condition into the member 30, for example. 'through apertures in the sides which are then closed by plugs 64. To prevent dseepage of oil therethrough the metals-used -in the construction of the'heater shouldbe close grained. Prefer'ably, Steel is used. All threadedfjoints are provided with ltapered threads so as' to be Voil-tight. Y While I have-described my invention as embbdied in concrete formand as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various -inoditications thereof will suggest 'themselves to those skilled in the art without departing from the spirit ofmy invention,,the scope of which is set forth in the annexed claims.

-eWhat I claim as new and desire to secure by Letters Patent of the United States is 1. An electric heater comprising a tubular member, a vplurality of electric heating units' grouped aroundsaid memberviin good heat eonductlng relation therewith, a 4conductingrod extendingthrough said tubular member forming'a 'part of a heating' circuit for said units, and fusible cut-out in said conducting rod.

2. VAn electric heater comprising a metallic j ubular member, `a plurality of. electric heatfing units' Vsecured around said .member in good heat condu'ctingfre'lationl therewith, a

conducting rod extending' through said tubular.` member forming a part of the electric circuit for said units, a fusible cut-out with, a cdnducting-rod extending throughv in said conducting rod, and means for applying a tension to said rod whereby cutout. isruptured toopen the heating circuit upon the occurrence of a predetermined temperature.

3.'An electric Y heater comprising. a mer tallic tubular member, a plurality' of elec- Ytric heating 'units securedaround said member in good heat" conducting relation theresaid tubular memberforming a part 'of the electric circuit for said units, a fusible'cuti 'outin- 'said conducting rod, headH members secured to and closing the ends of said tujbular member, an electrical conductor mechanically secured to onev of said head mem- .'bersjwhereb' the heater may be lifted, vand an 'electrical' connection) between said conductorfandfsaidrod.. f c.

Y 4.' An electric heater comprising a' tu-- bular member upper and lower. heads se- Acured to and c sing the ends off'said tubular member, elongated heating 'arranged' head members, a tubular member connecting A said head members, a plurality of heating units Vsecured around said tubular member 1n good heat conducting heat relation therelwith, a common electrical connection for sal said4 heating units in one of said head members, a conducting rod extending through sald tubular member, an electrical connection between one, end of said rod and said common connection, fusible cut-outs spaced at intervals along said rod, and means for r applying a tension torsaid roxd whereb the' electric heating circuit vis opened t erethrough' upon the occurrence of a predetermined temperature.

6. An Lelectric heater hrranged to belowered into an oil well comprising upper and Y. lower hollow heads, a tubular member coni necting heads, a pluralit of elol ted heating Hinits secured aroun said'tu ular member in good heat conducting relationtherewith, the lower ends of said units extendin into said lower head member, 'a common e ectrical connection for said' heating units in said lower head member, a--conducting rod electrically connected to said common connectionand extending upward centrally of said tubular member, an electrical conductor mechanically secured to said upper head and electrically connected tosaid rod,

means for applying tension to said rod, and

fusible' cut-outsspaced at Aintervals in said i 7 The combination. with anelectric heater,

ofv a metallic member included inthe circuit of said heater adapted -to'fuse and open the 'circuit ofsaid heater upon the occurrence of a predetermined temperature, and a second metallic member having a lower melting point enclosed bythe first arranged to4 fuse and extinguish the electric are formed when the circuit of said heater is opened by rupture 4of said first member. 8. The combination withanelectric heater, of anl outer member made of aluminum inmember arranged to fuse before 'said .outer member and extinguish the electric arc' formed when the circuit of said heater :isf opened4 by rupture of said louter member- 'upon the oecu'rrenceofa predetermined temperature. l y

9, The. combination with an electric heater, of an outer tubular member included in thel 12o' elude-d in the circuit of heater, and an' i inner member 'made of zinc inside s ald outerV circuit of said heater, :1nd a rod of a metal having a lower melting point inside said tubular member arranged to fuse. and extinguish the electric arc formed when the circuit of said heater is openedby rupture sections, a tubular member madeof alumi-v num forming a mechanical connection bef Y tween sald` sectlons and normally eloslngthe circuit of said heater through said s ections, means for applying a: tension to said rod, and azinc rod inside saidtubular memv ber arranged to fuse' and extinguish the arc formed when the circuit of said heater is opened by rupture of said tubular member' upon the occurrence of a predetermined temperature.

In witnesswhereof, I have hereunto set of November 1924.

my hand this 20th da 'CHAR ES C.ABBOTT. 

